fix: add fallback UUID generator for crypto.randomUUID compatibility

crypto.randomUUID() is not available in all environments (e.g., older browsers,
non-secure contexts). Added a fallback UUID v4 implementation.

src/frontend/src/lib/stores/chatStore.ts

@@ -8,12 +8,25 @@ export interface ChatMessage {
 	timestamp: Date;
 }
 
+// Fallback UUID generator for environments where crypto.randomUUID is not available
+function generateId(): string {
+	if (typeof crypto !== 'undefined' && typeof crypto.randomUUID === 'function') {
+		return crypto.randomUUID();
+	}
+	// Fallback: simple UUID v4 implementation
+	return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, (c) => {
+		const r = (Math.random() * 16) | 0;
+		const v = c === 'x' ? r : (r & 0x3) | 0x8;
+		return v.toString(16);
+	});
+}
+
 export const chatStore = writable<ChatMessage[]>([]);
 
 export function addMessage(message: Omit<ChatMessage, 'id' | 'timestamp'>) {
 	const newMessage: ChatMessage = {
 		...message,
-		id: crypto.randomUUID(),
+		id: generateId(),
 		timestamp: new Date()
 	};
 	chatStore.update(messages => [...messages, newMessage]);